From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-24.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83076C2B9F4 for ; Fri, 25 Jun 2021 20:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 556946195F for ; Fri, 25 Jun 2021 20:13:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229816AbhFYUP3 (ORCPT ); Fri, 25 Jun 2021 16:15:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:40264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229573AbhFYUP2 (ORCPT ); Fri, 25 Jun 2021 16:15:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C4FFE61879; Fri, 25 Jun 2021 20:13:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624651987; bh=9dGndesqenWa7LqpmTkh/VkTIUvlXFjI1oyySUK2Wio=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=obrIPNX2aRIOkzMAHxdZGVi1I2p+g8oAjPThh3wEYCpo3uYI7FekdIHmsZ+XznjEl 2RN7Sbk1p9e2XjwPCd5iITm0snR5mzy70ODfSnj2yLHHsTzw13R0Sd4nBwfSXTFdTH bPyRrcUra+rY2wqScCtcuhr1PjMaZ/pXhGIiokDxjfRRDJzDpks1X5v3mHZ6Bw28us GxH1ZTZVO6v+3J1Qdm1p70LRUbOlZROaTaphzhwQd0O9adnB9V+KtJRs6MobbMXlzk OlfGw5UN268kdztPfyOcJXpQ1tcWmmbpK8j9YIdci9xFrLBaKggzfVbJjGHYVdJ6jA aADVUNzS3B4hA== From: Nathan Chancellor To: "Geoffrey D. Bennett" , Jaroslav Kysela , Takashi Iwai Cc: Nick Desaulniers , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, Nathan Chancellor Subject: [PATCH v4] ALSA: usb-audio: scarlett2: Fix for loop increment in scarlett2_usb_get_config Date: Fri, 25 Jun 2021 13:11:51 -0700 Message-Id: <20210625201150.1523987-1-nathan@kernel.org> X-Mailer: git-send-email 2.32.0.93.g670b81a890 In-Reply-To: <20210625200549.1061113-1-nathan@kernel.org> References: <20210625200549.1061113-1-nathan@kernel.org> MIME-Version: 1.0 X-Patchwork-Bot: notify Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clang warns: sound/usb/mixer_scarlett_gen2.c:1189:32: warning: expression result unused [-Wunused-value] for (i = 0; i < count; i++, (u16 *)buf++) ^ ~~~~~ 1 warning generated. It appears the intention was to cast the void pointer to a u16 pointer so that the data could be iterated through like an array of u16 values. However, the cast happens after the increment because a cast is an rvalue, whereas the post-increment operator only works on lvalues, so the loop does not iterate as expected. Replace the cast with a temporary variable of the proper type, which is less error prone and fixes the iteration. Do the same thing for the 'u8 *' below this if block. Fixes: ac34df733d2d ("ALSA: usb-audio: scarlett2: Update get_config to do endian conversion") Link: https://github.com/ClangBuiltLinux/linux/issues/1408 Acked-by: Geoffrey D. Bennett Signed-off-by: Nathan Chancellor --- v1 -> v2: * Use temporary variables of proper type rather than casting, as requested by Takashi. * Mention that there is not a bug at the moment per Geoffrey's comment. v2 -> v3: * Restrict scope of buf_16 more, as requested by Geoffrey. * Add Geoffrey's ack. v3 -> v4: * Fix stray newline added below if (config_item->size >= 8) { leftover from buf_16's declaration. sound/usb/mixer_scarlett_gen2.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c index fcba682cd422..161d832cafef 100644 --- a/sound/usb/mixer_scarlett_gen2.c +++ b/sound/usb/mixer_scarlett_gen2.c @@ -1177,6 +1177,7 @@ static int scarlett2_usb_get_config( const struct scarlett2_config *config_item = &scarlett2_config_items[info->has_mixer][config_item_num]; int size, err, i; + u8 *buf_8; u8 value; /* For byte-sized parameters, retrieve directly into buf */ @@ -1185,9 +1186,12 @@ static int scarlett2_usb_get_config( err = scarlett2_usb_get(mixer, config_item->offset, buf, size); if (err < 0) return err; - if (size == 2) - for (i = 0; i < count; i++, (u16 *)buf++) - *(u16 *)buf = le16_to_cpu(*(__le16 *)buf); + if (size == 2) { + u16 *buf_16 = buf; + + for (i = 0; i < count; i++, buf_16++) + *buf_16 = le16_to_cpu(*(__le16 *)buf_16); + } return 0; } @@ -1197,8 +1201,9 @@ static int scarlett2_usb_get_config( return err; /* then unpack from value into buf[] */ + buf_8 = buf; for (i = 0; i < 8 && i < count; i++, value >>= 1) - *(u8 *)buf++ = value & 1; + *buf_8++ = value & 1; return 0; } base-commit: 0cbbeaf370221fc469c95945dd3c1198865c5fe4 -- 2.32.0.93.g670b81a890